1
Atsushi Nagata, Yutaka Uekawa, Takanori Senoo, Kenichi Takahashi: Method and apparatus for protection of signal copy. Matsushita Electric Industrial, Wenderoth Lind & Ponack, December 18, 1990: US04979210 (292 worldwide citation)

An apparatus for the protection of signal copy for prevention unauthorized copying of music software such as records, compact discs and music tape by recording is arranged such that when recording audio signals on a medium, certain supplemental information is added to the audio signal to be recorded ...


2
Atsushi Nagata, Yutaka Uekawa, Takanori Senoo, Kenichi Takahashi: Method and apparatus for the protection of signal copy. Matsushita Electric Industrial, Wenderoth Lind & Ponack, December 17, 1991: US05073925 (217 worldwide citation)

An apparatus for the protection of signal copy for preventing unauthorized copying of music software such as records, compact discs and music tape by recording is arranged such that when recording audio signals on a medium, certain supplemental information is added to the audio signal to be recorded ...


3
Yutaka Uekawa, Shuji Takata, Michiyo Goto: Method for extracting formant frequencies. Matsushita Electric Industrial, Wenderoth Lind & Ponack, November 21, 1989: US04882758 (21 worldwide citation)

A high speed method for formant extraction includes the steps of calculating linear prediction coefficients by executing linear prediction analysis of an input speech signal, extracting a coarse formant frequency by making a linear combination of multiple regression coefficients obtained through mul ...